Means for coating metal pipes



UNITED STATES PATENT- OFFICE.

JOHN D. HOOKER, 0F LOS ANGELES, CALIFORNIA.

MEANS FOR COATING METAL PIPES.

I SPECIFICATION forming part of Letters Patent No. 425,675, dated April 15, 1890.

Application filed February 20, 1888- $erial No. 264,636. (Model!) To all whom it may concern.-

Be itknown that 1, JOHN D. HOOKER, of the city and county of Los Angeles, State of California, have invented an Improved Means for Coating Metal Pipes, of which the following is a specification.

My invention relates to the coating of pipes both inside and outside, such as are used for conducting water for irrigating, mining, and other purposes.

The invention consists in the application, in a heated bath, of the substance known in the arts as maltha to the inside and out side surfaces of the pipe, said substance being produced by a process of distillation of crude petroleum.

Heretofore pipes have been dipped in a heated bath of asphaltum and tar, and the coating thus formed upon the pipes was found to protect the pipes from rust in a measurable degree; but the asphaltum bath has been found unsatisfactory, because the asphaltum does not always thoroughly adhere to the surfaces, often cracking and chipping off in large flakes; also, the effect of extreme heat and cold has been found to seriously impair the coating. So with water containing alkali, the coating has been found entirely eaten away from the interior after a few months of use; and, finally, the most dexterous manipulation of the pipes in the bath failed to give the pipes a smooth even surface, but thick ridges would form as the pipe cooled, which often considerably reduced the interior area, so that the capacity of the pipe was reduced (in the cases of the smaller pipes) often to the extent of ten per cent. of its original capacity.

Now, I have discovered after much experimenting that a purified article of maltha, the gummy residuum of the still wherein certain grades of crude petroleum have been distilled,wl1en properly reheated in abath and reduced by the admixture of a quantity of crude oil, will form a thoroughly satisfactory coa'ting for pipes, having the great advantage of closely adhering and even penetrating the metal, so that it is almost impossible to scrape it off when once applied. It is also unaffected by alkali in the water, never imparts a taste or smell to the water, and always distributes itself in an even bright coating upon the surface of the pipe; besides it withstands the variations of temperature much better than asphaltum.

I am aware that maltha is found in a natural state, but this natural product is invariably mixed with Water, sand, and other impurities, and in its .natural state does not serve as a good coating, being little better than asphaltum; but if produced as a residuum of the still it acquires a bright, clear, and homogeneous texture, which the natural product found deposited in the ground does not possess.

I speak above of diluting the heated maltha with crude oil. This is not always necessary, for often the maltha itself will melt to a consistency which adapts it for applica tion without diluting it; but when it has boiled in the heating-kettle for some time it becomes thickened, so that to make it of the proper consistency its reduction or dilution becomes necessary. This may be done by pouring into the kettle either a quantity of crude oil or tar.

What I claim as my invention, and desire to secure by Letters Patent, isas follows:

A metallic pipe having a coating both inside and outside of the gummy residuum produced in the distillation of certain crude petroleums and commercially known as purified maltha, said coating being applied in a heated bath, substantially as and for the purpose herein described.

JOHN D. HOOKER. \Vitnesses:

GEORGE PARDY, F. K. SIMONDS. 

